Round 1: Tossup 7
By the KSS bound, the ratio of eta to entropy density of these substances is lower bounded by one over 4pi. The stress-energy tensor of an ideal one of these substances is rho plus p times a product of 4-velocities plus p times the metric tensor. In the rest frame, a “perfect” one of these substances is parametrized by its isotropic pressure and energy density, and therefore has a diagonal stress-energy tensor. By definition, these substances have zero shear modulus, meaning they cannot undergo shear stress without deformation. Many Bose–Einstein condensates act like an idealized “super” one of these substances that move without dissipating energy. The Navier–Stokes equations are central equations in the “mechanics” of, for 10 points, what substances that can flow, including liquids and gases? ■END■
ANSWER: fluids [accept ideal fluids; accept perfect fluids; accept superfluids; accept fluid mechanics; accept Newtonian fluids; prompt on liquids, gases, quark–gluon plasmas, or QGPs by asking “that is a specific example of what more generally defined substances?”] (Eta in the first clue is shear viscosity; the clue refers to the shear viscosity to entropy density ratio.)
<GC, Physics> | Packet A - Brown A, Wisconsin A, Purdue, Maryland B
= Average correct buzzpoint
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